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- Allow a database search to be narrowed, broadened or made more precise.
- There are three Boolean operators: AND, OR, and NOT.
- AND, OR, NOT are inserted between each search term.
- Used for narrowing or focusing a search topic.
- Specifies that both search terms must be present in the results.
Example: Teenagers AND Violence
- Used for expanding or broadening a search topic.
- Specifies that either search term can be present in the results.
- Often used to include synonyms or related terms.
Example: Teenager OR Juvenile OR Adolescent
- Used to eliminate false hits, or get rid of that one term that you don't want in your results list.
- Specifies that the first term but not the second can be present in the results.
Example: Teenagers NOT Violence.
Nesting, Truncation and Wildcards
Nesting or Parentheses
- An alternative to a database's Advanced Search
- Allows you to construct complex searches combining AND, OR, NOT by grouping search terms appropriately
(Teenagers OR Juveniles) AND Violence
- Expands the search to locate all words beginning with the same root
- Symbol to truncate is usually an asterisk (*)
- Example: teen* will return teen, teens, teenage, teenager, etc.
- Useful to include any variants authors might use to describe their research
- Not all words can effectively be truncated
- Example: Trying to truncate woman as wom* will return wombat, womb, as well as woman and women.
- Used in the middle of a word to match usually known variants of a term.
- A wildcard usually represents a single character
- Symbol to represent the single character is usually a question mark (?) but this can vary by database.
- Example: wom?n will return woman, women, and womyn.
Note: These search tools involve using various symbols. The symbols change depending on the database's vendor/interface you're dealing with, and the symbols may change over time within one of these vendors/interfaces. If you have any questions about what symbols are used in a database, check its "Help" section.
Do you have any further questions about Boolean Operators and other database tips and tricks? Chat with a Reference Librarian!